Investigation into the Dynamics and Control of an Underwater Vehicle-Manipulator System

This study addresses the detailed modeling and simulation of the dynamic coupling between an underwater vehicle and manipulator system. The dynamic coupling effects due to damping, restoring, and inertial effects of an underwater manipulator mounted on an autonomous underwater vehicle (AUV) are analyzed by considering the actuator and sensor characteristics. A model reference control (MRC) scheme is proposed for the underwater vehicle-manipulator system (UVMS). The effectiveness of the proposed control scheme is demonstrated using numerical simulations along with comparative study between conventional proportional-integral-derivative (PID) control. The robustness of the proposed control scheme is also illustrated in the presence of external disturbances and parameter uncertainties

The effect of surface treatment on composite interface, tensile properties and water absorption of suger palm fiber/polypropylene composites

The rising concern towards environmental issues besides the requirement for more flexible polymer-based material has led to increasing of interest in studying about green composite. Sugar palm fiber (SPF) is a versatile fiber plant employed with wide range of application such as in automotive, packaging and buildings construction. This research was aimed to study the effect of surface treatment on composite interface, tensile properties and water absorption of sugar palm fiber/polypropylene (SPFPP) composite by using different surface treatments such as silane (Si), atmospheric glow discharge plasma (Agd) and maleic anhydride (Ma). Silane treatment was carried out by using immersion method, the Agd plasma was conducted using polymerization and lastly polypropylene grafted maleic anhydride by using melting approach. The SPFPP composite was prepared by using injection moulding with fiber content var­ied from 10-30wt%. The effect of interface enhancement on morphology, mechanical properties and water uptakes of SPFPP composites were then investigated by using FfIR, FESEM, tensile test and water absorption test. Overall, the outcome shows that aJl types of surface treatments had improved the interface of SPFPP composite, thus improving its tensile properties compared to the benchmark untreated SPFPP (Ut­SPFPP) composites and polypropylene. The 30wt% Ma-SPFPP composite shows the highest improvement in tensile properties with 58% and 27% increase in the respective Young's Modulus and tensile strength value compared to Ut-SPFPP composite, while 10wt% Ma-SPFPP composite shows the smallest reduction in elongation compared to Neat PP. On the other hand, the 30wt% Si-SPFPP composite shows the lowest water absorption with 20% reduction respective to Ut-SPFPP composite. In conclusion, the surface treatments have proven succesfull in enhancing the natural fiber-polymer in­terface and improve the tensile properties of SPFPP composite with Ma-SPFPP shows the highest improvement, foJlowed by Agd-SPFPP and Si-SPFPP composites

The effect of surface treatment on composite interface, tensile properties and water absorption of suger palm fiber/polypropylene composites

The rising concern towards environmental issues besides the requirement for more flexible polymer-based material has led to increasing of interest in studying about green composite. Sugar palm fiber (SPF) is a versatile fiber plant employed with wide range of application such as in automotive, packaging and buildings construction. This research was aimed to study the effect of surface treatment on composite interface, tensile properties and water absorption of sugar palm fiber/polypropylene (SPFPP) composite by using different surface treatments such as silane (Si), atmospheric glow discharge plasma (Agd) and maleic anhydride (Ma). Silane treatment was carried out by using immersion method, the Agd plasma was conducted using polymerization and lastly polypropylene grafted maleic anhydride by using melting approach. The SPFPP composite was prepared by using injection moulding with fiber content var­ied from 10-30wt%. The effect of interface enhancement on morphology, mechanical properties and water uptakes of SPFPP composites were then investigated by using FfIR, FESEM, tensile test and water absorption test. Overall, the outcome shows that aJl types of surface treatments had improved the interface of SPFPP composite, thus improving its tensile properties compared to the benchmark untreated SPFPP (Ut­SPFPP) composites and polypropylene. The 30wt% Ma-SPFPP composite shows the highest improvement in tensile properties with 58% and 27% increase in the respective Young's Modulus and tensile strength value compared to Ut-SPFPP composite, while 10wt% Ma-SPFPP composite shows the smallest reduction in elongation compared to Neat PP. On the other hand, the 30wt% Si-SPFPP composite shows the lowest water absorption with 20% reduction respective to Ut-SPFPP composite. In conclusion, the surface treatments have proven succesfull in enhancing the natural fiber-polymer in­terface and improve the tensile properties of SPFPP composite with Ma-SPFPP shows the highest improvement, foJlowed by Agd-SPFPP and Si-SPFPP composites

Task-space dynamic control of underwater robots

This thesis is concerned with the control aspects for underwater tasks performed by marine robots. The mathematical models of an underwater vehicle and an underwater vehicle with an onboard manipulator are discussed together with their associated properties. The task-space regulation problem for an underwater vehicle is addressed where the desired target is commonly specified as a point. A new control technique is proposed where the multiple targets are defined as sub-regions. A fuzzy technique is used to handle these multiple sub-region criteria effectively. Due to the unknown gravitational and buoyancy forces, an adaptive term is adopted in the proposed controller. An extension to a region boundary-based control law is then proposed for an underwater vehicle to illustrate the flexibility of the region reaching concept. In this novel controller, a desired target is defined as a boundary instead of a point or region. For a mapping of the uncertain restoring forces, a least-squares estimation algorithm and the inverse Jacobian matrix are utilised in the adaptive control law. To realise a new tracking control concept for a kinematically redundant robot, subregion tracking control schemes with a sub-tasks objective are developed for a UVMS. In this concept, the desired objective is specified as a moving sub-region instead of a trajectory. In addition, due to the system being kinematically redundant, the controller also enables the use of self-motion of the system to perform sub-tasks (drag minimisation, obstacle avoidance, manipulability and avoidance of mechanical joint limits)

Modelling and control of lightweight underwater vehicle-manipulator systems

This thesis studies the mathematical description and the low-level control structures for underwater robotic systems performing motion and interaction tasks. The main focus is on the study of lightweight underwater-vehicle manipulator systems. A description of the dynamic and hydrodynamic modelling of the underwater vehicle-manipulator system (UVMS) is presented and a study of the coupling effects between the vehicle and manipulator is given. Through simulation results it is shown that the vehicle’s capabilities are degraded by the motion of the manipulator, when it has a considerable mass with respect to the vehicle. Understanding the interaction effects between the two subsystems is beneficial in developing new control architectures that can improve the performance of the system. A control strategy is proposed for reducing the coupling effects between the two subsystems when motion tasks are required. The method is developed based on the mathematical model of the UVMS and the estimated interaction effects. Simulation results show the validity of the proposed control structure even in the presence of uncertainties in the dynamic model. The problem of autonomous interaction with the underwater environment is further addressed. The thesis proposes a parallel position/force control structure for lightweight underwater vehicle-manipulator systems. Two different strategies for integrating this control law on the vehicle-manipulator structure are proposed. The first strategy uses the parallel control law for the manipulator while a different control law, the Proportional Integral Limited control structure, is used for the vehicle. The second strategy treats the underwater vehicle-manipulator system as a single system and the parallel position/force law is used for the overall system. The low level parallel position/force control law is validated through practical experiments using the HDT-MK3-M electric manipulator. The Proportional Integral Limited control structure is tested using a 5 degrees-of-freedom underwater vehicle in a wave-tank facility. Furthermore, an adaptive tuning method based on interaction theory is proposed for adjusting the gains of the controller. The experimental results show that the method is advantageous as it decreases the complexity of the manual tuning otherwise required and reduces the energy consumption. The main objectives of this thesis are to understand and accurately represent the behaviour of an underwater vehiclemanipulator system, to evaluate this system when in contact with the environment and to design informed low-level control structures based on the observations made through the mathematical study of the system. The concepts presented in this thesis are not restricted to only vehicle-manipulator systems but can be applied to different other multibody robotic systems

Underwater Robots Part II: Existing Solutions and Open Issues

National audienceThis paper constitutes the second part of a general overview of underwater robotics. The first part is titled: Underwater Robots Part I: current systems and problem pose. The works referenced as (Name*, year) have been already cited on the first part of the paper, and the details of these references can be found in the section 7 of the paper titled Underwater Robots Part I: current systems and problem pose. The mathematical notation used in this paper is defined in section 4 of the paper Underwater Robots Part I: current systems and problem pose

Six degree of freedom vehicle controller design for the operation of an unmanned underwater vehicle in a shallow water environment

Thesis (Ocean E)--Massachusetts Institute of Technology, Dept of Ocean Engineering, 1994, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1994GRSN 707418Includes bibliographical references (leaves 103-104).by Michael F. Hajosy.M.S.Ocean

Underwater Vehicles

For the latest twenty to thirty years, a significant number of AUVs has been created for the solving of wide spectrum of scientific and applied tasks of ocean development and research. For the short time period the AUVs have shown the efficiency at performance of complex search and inspection works and opened a number of new important applications. Initially the information about AUVs had mainly review-advertising character but now more attention is paid to practical achievements, problems and systems technologies. AUVs are losing their prototype status and have become a fully operational, reliable and effective tool and modern multi-purpose AUVs represent the new class of underwater robotic objects with inherent tasks and practical applications, particular features of technology, systems structure and functional properties

MUSME 2011 4 th International Symposium on Multibody Systems and Mechatronics

El libro de actas recoge las aportaciones de los autores a través de los correspondientes artículos a la Dinámica de Sistemas Multicuerpo y la Mecatrónica (Musme). Estas disciplinas se han convertido en una importante herramienta para diseñar máquinas, analizar prototipos virtuales y realizar análisis CAD sobre complejos sistemas mecánicos articulados multicuerpo. La dinámica de sistemas multicuerpo comprende un gran número de aspectos que incluyen la mecánica, dinámica estructural, matemáticas aplicadas, métodos de control, ciencia de los ordenadores y mecatrónica. Los artículos recogidos en el libro de actas están relacionados con alguno de los siguientes tópicos del congreso: Análisis y síntesis de mecanismos ; Diseño de algoritmos para sistemas mecatrónicos ; Procedimientos de simulación y resultados ; Prototipos y rendimiento ; Robots y micromáquinas ; Validaciones experimentales ; Teoría de simulación mecatrónica ; Sistemas mecatrónicos ; Control de sistemas mecatrónicosUniversitat Politècnica de València (2011). MUSME 2011 4 th International Symposium on Multibody Systems and Mechatronics. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/13224Archivo delegad